Rydberg states in molecular aggregates as a route to new optoelectronic materials

普渡大学的Lyudmila V. Slipchenko获得了化学系化学理论，模型和计算方法项目的奖项，以开发描述利用光能进行有用应用的系统的方法。 这种机制的一个例子是植物的光合作用，但有许多人工系统试图模仿植物。 通常这种类型的系统具有紧凑的电荷分布，但最近的工作表明，具有扩散电荷分布的状态也能够捕获和使用光能。 这些状态已被证明存在于各种纳米材料中，包括石墨烯片、纳米管和富勒烯，这些状态有望开发出一类具有上级性能的新材料，用于电子应用。Slipchenko博士和她的团队正在开发理论和计算方法，用于精确描述分子晶体中的这种扩散状态。 有了这些方法，Slipchenko博士还在探索通过分子簇中的这些扩散态进行能量和电子传输的可能性。该项目开发的新方法和算法分布广泛，可作为预测化学，生物学和材料中光诱导现象行为的强大工具。Slipchenko博士是女学生和博士后的榜样，并在职业生活平衡的挑战中提供支持和建议。她还组织国家和国际会议，努力提高年轻女科学家的参与度和知名度。 Slipchenko博士和她的团队开发了理论和计算方法，可用于严格描述扩展系统中的扩散Rydberg和Rydberg样状态，例如与光电材料相关的分子晶体和由光合复合物激发的天然有机聚集体。该方法是基于一个完全嵌入的量子力学/分子力学（QM/MM）的方法，其中的环境（MM部分）是由复杂的从头计算为基础的有效碎片势（EFP），和QM和MM子系统之间的相互作用，包括静电，极化，色散和交换排斥条款，所有这些都是在量子力学水平上描述。在这个项目中，Slipchenko博士和她的团队正在探索通过利用分子材料中的里德伯态进行能量和电子传输的可能性，方法是开发用于电子激发态的完全嵌入QM/EFP方法，并开发描述分子晶体和其他多发色团系统中激子相互作用和传输的振动耦合模型。该项目通过将新的计算机代码集成到开源、免费提供的libefp库和开源PSI 4、GAMESS、NWChem和MOLCAS电子结构包中，以及Q-Chem量子化学软件中的开源模块，为研究基础设施做出了贡献。用于预测分子聚集体中电子振动相互作用和能量/电子传输的基于网络的交互式软件正在开发中，可在普渡大学NanoHUB获得。 该软件可作为量子力学、光谱学和纳米技术课程的教学工具。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Lyudmila V. Slipchenko of Purdue University is supported by an award from the Chemical Theory, Models and Computational Methods program in the Chemistry Division to develop methods to describe systems that harness light energy for useful applications. One example of a mechanism of this type is photosynthesis in plants, but there are a host of artificial systems that attempt to mimic plants. Usually systems of this type have compact charge distributions, but recent work has shown that states with diffuse charge distributions may also be capable of capturing and using light energy. These states have been shown to exist in a variety of nanomaterials, including graphene sheets, nanotubes and fullerenes, and these states holds promise to develop a new class of materials with superior properties for electronics applications. Dr. Slipchenko and her group are developing theoretical and computational methods for the accurate description of such diffuse states in molecular crystals. Armed with these methods, Dr. Slipchenko is also exploring possibilities for energy and electron transport through these diffuse states in molecular clusters. New methods and algorithms developed in this project are broadly distributed and serve as robust tools to predict the behavior of light-induced phenomena in chemistry, biology, and materials. Dr. Slipchenko serves as a role model for female students and postdocs and provides support and advice in career-life balancing challenges. She also organizes national and international conferences and works to increase the participation and visibility of young female scientists. Dr. Slipchenko and her group develop theoretical and computational methodologies that can be applied for rigorous description of diffuse Rydberg and Rydberg-like states in extended systems such as molecular crystals of relevance to optoelectronic materials and natural organic aggregates motivated by photosynthetic complexes. The methodology is based on a fully embedded quantum mechanics / molecular mechanics (QM/MM) approach, in which the environment (MM part) is described by the sophisticated ab initio-based Effective Fragment Potential (EFP), and the interaction between QM and MM subsystems includes electrostatic, polarization, dispersion and exchange-repulsion terms, all of which are described at a quantum-mechanical level. In this project, Dr. Slipchenko and her group are exploring possibilities for energy and electron transport through utilization of Rydberg states in molecular materials by development of full embedding QM/EFP methods for electronic excited states and development of vibronic coupling models that describe exciton interactions and transport in molecular crystals and other multi-chromophore systems. The project contributes to the research infrastructure by integrating new computer codes in the open-source, freely available libefp library and in the open-source PSI4, GAMESS, NWChem and MOLCAS electronic structure packages, as well as open-source modules in the Q-Chem quantum chemistry software. Web-based interactive software for predicting vibronic interactions and energy/electron transport in molecular aggregates is being developed and is available at the Purdue University NanoHUB. The software can be adapted as a teaching tool in quantum mechanics, spectroscopy and nanotechnology courses.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.